1. Field of the Invention
The present invention relates to resin multilayer substrates.
2. Description of the Related Art
A known technique for obtaining a resin multilayer substrate is stacking films made of thermoplastic resin to form a multilayer body and integrating them. The resin multilayer substrate may incorporate a component. One such example is described in Japanese Unexamined Patent Application Publication No. 2003-86949. The resin multilayer substrate may have a structure in which a plurality of conductive vias are connected in series along a laminating direction (hereinafter referred to as “serial via section”) for causing wiring to extend from the incorporated component.
In the serial via section, the conductive vias and conductive patterns are electrically connected such that they are alternately linked. To the serial via section, breaks between the conductive vias and the conductive patterns may occur. Because the serial via section has higher stiffness than that of other sections (resin layers) in the multilayer body, the coplanarity of the top surface of the multilayer body may degrade when the multilayer body is pressed for integration. If the coplanarity of the top surface degrades, when mounting a component on the surface, the component may be mounted improperly. If a narrow interval is set between incorporated components, the shape of one or more serial via sections may be distorted at the time of pressing for integration of the multilayer body, the plurality of serial via sections may come into contact with each other, and this may cause electrical short circuits. In addition, because the incorporated components also have higher stiffness than that of the resin layers in the multilayer body, for the same reason, electrical short circuiting caused by contact between the components is also a problem.
Because the serial via sections, incorporated components, and other elements, have high stiffness, the coplanarity of the top surface of the multilayer body may degrade in the area in which such serial via sections, incorporated components, and other elements are disposed at the time of pressing for integration of the multilayer body. If the coplanarity of the top surface degrades, when mounting a component on the top surface, the component may be mounted improperly.